EP0827941B1 - Sinterable lithium disilicate glass-ceramics - Google Patents

Sinterable lithium disilicate glass-ceramics Download PDF

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Publication number
EP0827941B1
EP0827941B1 EP97250239A EP97250239A EP0827941B1 EP 0827941 B1 EP0827941 B1 EP 0827941B1 EP 97250239 A EP97250239 A EP 97250239A EP 97250239 A EP97250239 A EP 97250239A EP 0827941 B1 EP0827941 B1 EP 0827941B1
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EP
European Patent Office
Prior art keywords
glass
glass ceramic
dental
components
lithium disilicate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP97250239A
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German (de)
French (fr)
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EP0827941A1 (en
Inventor
Marcel Dipl.-Ing. Schweiger
Martin Dipl.-Ing. Frank
Volker Dr. Rheinberger
Wolfram Professor Dr. Höland
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Ivoclar Vivadent AG
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Ivoclar AG
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Priority claimed from DE19647739A external-priority patent/DE19647739C2/en
Application filed by Ivoclar AG filed Critical Ivoclar AG
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C4/00—Compositions for glass with special properties
    • C03C4/0007—Compositions for glass with special properties for biologically-compatible glass
    • C03C4/0021—Compositions for glass with special properties for biologically-compatible glass for dental use
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/70—Preparations for dentistry comprising inorganic additives
    • A61K6/78—Pigments
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
    • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
    • A61K6/807—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising magnesium oxide
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
    • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
    • A61K6/813—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising iron oxide
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
    • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
    • A61K6/818—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising zirconium oxide
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
    • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
    • A61K6/822—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising rare earth metal oxides
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
    • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
    • A61K6/824—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising transition metal oxides
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
    • A61K6/831—Preparations for artificial teeth, for filling teeth or for capping teeth comprising non-metallic elements or compounds thereof, e.g. carbon
    • A61K6/833—Glass-ceramic composites
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
    • C03C10/0009—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing silica as main constituent
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
    • C03C10/0018—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and monovalent metal oxide as main constituents
    • C03C10/0027—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and monovalent metal oxide as main constituents containing SiO2, Al2O3, Li2O as main constituents

Definitions

  • the invention relates to sinterable lithium disilicate glass ceramics and especially those that differ due to their properties for the production of molded dental products by plastic deformation under the influence of pressure and heat.
  • Lithium disilicate glass ceramics are known from the prior art.
  • EP-B-536 479 describes self-glazed lithium disilicate glass ceramic articles, but these are not intended for dental applications.
  • the glass ceramics are free of La 2 O 3 and are formed in a conventional manner by melting suitable starting materials, pouring them into molds and then heat treating the objects obtained.
  • Lithium-silicate glass ceramics are also disclosed in EP-B-536 572. By sprinkling a finely divided colored glass on their surface, they are given structure and color, and they are used as lining elements for building purposes. They are manufactured in a conventional manner by melting suitable starting materials, shaping the melt into a desired body and heat-treating the body together with scattered colored glass. However, La 2 O 3 is not included in the glass ceramic.
  • the state of the art also discloses the use of lithium disilicate glass ceramics in dental technology, but these glass ceramics all contain no La 2 O 3 or MgO and only conventional methods are used for their processing into dental products, in which a heat treatment to eliminate Crystals only on homogeneous bodies, namely monoliths formed from a glass melt, such as small glass blocks or platelets.
  • a heat treatment to eliminate Crystals only on homogeneous bodies, namely monoliths formed from a glass melt, such as small glass blocks or platelets.
  • such conventional methods only allow bulk crystallization, but not surface crystallization.
  • a high-strength lithium disilicate glass ceramic also describes US-A-4,189,325, this glass ceramic being required for CaO Flow improvement as well as platinum and niobium oxide for the production of contains very fine and uniform crystals.
  • FR-A-2 655 264 contains lithium oxide and silicon oxide Glass ceramics for the production of dental prostheses are described, which contain very large amounts of MgO.
  • US-A-5,507,981 and WO-A-95/32678 describe Lithium disilicate glass ceramics made by special processes shaped dental products can be further processed at which compress in the viscous, flowable state elevated temperatures to the desired dental product. More information on the manufacture of the used Tiles are not made. Also, the generation of Glass ceramics are handled in a conventional manner by using homogeneous Vitreous bodies, such as platelets, are heat treated. A disadvantage of these methods is that they are due to the Use of a special compressible crucible for one Dental technicians are very expensive. The glass ceramic will continue Materials heated until no more crystals in the molten material are present, otherwise the viscosity too high for pressing to the desired dental product is. Accordingly, not a glass ceramic, but a glass processed.
  • the known lithium disilicate glass ceramics show shortcomings, especially when it comes to sculpting them Processing condition to shaped dental products. For Such viscosity processing is not optimal adjusted so that a controlled flow is not possible and the reaction with the investment used was undesirably high is. Furthermore, conventional glass ceramics have only a small one Temperature stability, so that made from them Dental restorations only under deformation with a sintered Glass or glass ceramic layer can be provided. Finally, there is a lack of conventional lithium disilicate glass ceramics often also in the required chemical stability for use as a dental material in the oral cavity is constantly flushed with a wide variety of fluids.
  • the invention is accordingly based on the object of a lithium disilicate glass ceramic to provide the optimal one Flow behavior with little reaction with the Investment material when pressed in the plastic state into dental products shows a high temperature stability, in particular in the range of 700 to 900 ° C, and has an excellent has chemical stability.
  • the invention also relates to the method for Production of shaped dental products according to claims 7 to 13, the use of the glass ceramic according to claim 14, shaped dental products containing glass ceramic according to the Claims 15 and 16, and the glass according to claim 17.
  • the sinterable lithium disilicate glass ceramic according to the invention is characterized in that it contains the following components: component % By weight SiO 2 57.0 to 80.0 Al 2 O 3 0 to 5.0 La 2 O 3 0.1 to 6.0 MgO 0 to 5.0, especially 0.1 to 5.0 ZnO 0 to 8.0 K 2 O 0 to 13.5 Li 2 O 11.0 to 19.0 P 2 O 5 0 to 11.0 Color components 0 to 8.0 Additional components 0 to 6.0 in which (a) Al 2 O 3 + La 2 O 3 0.1 to 7.0% by weight and (b) MgO + ZnO 0.1 to 9.0% by weight make up and the color components of glass-coloring oxides (c) and / or color bodies (d) are formed in the following amounts: (c) glass coloring oxides 0 to 5.0% by weight and (d) Color bodies 0 to 5.0% by weight.
  • the glass ceramic preferably consists essentially of the previously mentioned components.
  • Preferred quantity ranges exist for the individual components of the lithium disilicate glass ceramic according to the invention. These can be selected independently of one another and are as follows: component % By weight SiO 2 57.0 to 75.0 Al 2 O 3 0 to 2.5 La 2 O 3 0.1 to 4.0 MgO 0.1 to 4.0 ZnO 0 to 6.0, especially 0.1 to 5.0 K 2 O 0 to 9.0, in particular 0.5 to 7.0 Li 2 O 13.0 to 19.0 P 2 O 5 0 to 8.0, in particular 0.5 to 8.0 Color components 0.05 to 6.0 Additional components 0 to 3.0.
  • the glass ceramic according to the invention preferably contains color components, namely glass-coloring oxides (c) and / or color bodies (d), in order to achieve a color adaptation of a dental product made from the glass ceramic to the natural tooth material of the patient.
  • the glass-coloring oxides in particular TiO 2 , CeO 2 and / or Fe 2 O 3 , merely provide a color tint, the main color being caused by the color bodies. It should be noted here that TiO 2 does not act as a nucleating agent, but in combination with the other oxides as a color component.
  • the metal bodies used are customary metal oxides and in particular commercially available isochromic color bodies, such as, for example, doped spinels and / or doped ZrO 2 .
  • the colored bodies can be both non-fluorescent and fluorescent materials.
  • the lithium disilicate glass ceramic according to the invention can also contain additional components, for which B 2 O 3 , F, Na 2 O, ZrO 2 , BaO and / or SrO are particularly suitable.
  • B 2 O 3 and F the viscosity of the residual glass phase of the glass ceramic can be influenced and it is assumed that they shift the ratio of surface to volume crystallization in favor of surface crystallization.
  • the glass ceramics according to the invention are produced the method described in more detail below Manufacture of molded dental products containing Glass ceramics are used, but special shapes can be omitted.
  • process step (a) an initial glass is melted, for which purpose suitable starting materials, such as carbonates, oxides and fluorides, intimately mixed together and to the specified Temperatures are heated, causing the exit glass forms. If coloring oxides are to be used, see above these are added to the batch. The addition of if necessary existing color bodies take place in a later stage of Process because its effect at high in the glass melt prevailing temperatures would be lost.
  • suitable starting materials such as carbonates, oxides and fluorides
  • stage (b) Poured into water and quenched into a glass granulate converted. This procedure is common also known as fries.
  • the glass granulate is then crushed in step (c) and in particular with conventional mills to the desired grain size ground.
  • an average grain size of the obtained Powder of 10 to 50 microns, based on the number of particles, preferred.
  • step (d) the addition of any that are present is then carried out Color bodies.
  • step (e) the powder is then compacted into a glass blank of the desired geometry and heterogeneous structure, with pressures of in particular 500 to 2,000 bar being used and in particular being carried out at room temperature.
  • This process step of pressing into a blank with a heterogeneous structure is important so that, in contrast to the methods known from the prior art, in the subsequent heat treatment in step (f), surface crystallization can also take place in addition to volume crystallization.
  • the heterogeneous structure of the starting glass blank consisting of compressed starting glass powder particles enables controlled surface crystallization on the inner surfaces of the glass powder.
  • the heat treatment in stage (f) is used for triggering the crystallization of the starting glass blank and thus for Formation of the glass ceramic after the completion of this process step is a densely sintered glass ceramic blank.
  • This Blank usually has the shape of a small cylinder or a small tile.
  • step (g1) the present as a blank Dental product at a temperature of 700 to 1200 ° C and through Application of pressure from 2 to 10 bar to a dental product desired geometry plastically deformed.
  • a blank Dental product at a temperature of 700 to 1200 ° C and through Application of pressure from 2 to 10 bar to a dental product desired geometry plastically deformed.
  • the press furnace used for this is the Empress® furnace from Ivoclar AG, Liechtenstein.
  • the dental product in the form of a blank has a viscosity of 10 5 to 10 6 Pa ⁇ s during plastic deformation in stage (g1).
  • the dental product present as a blank can also be used in Step (g2) mechanically desired to a dental product Geometry are processed, especially computer-aided Milling machines are used.
  • the dental product of the desired geometry obtained after step (g1) or (g2) is provided with a coating in step (h).
  • a ceramic, a sintered ceramic, a glass ceramic, a glass, a glaze and / or a composite are particularly suitable as coatings.
  • Coatings which have a sintering temperature of 650 to 950 ° C. and a linear coefficient of thermal expansion which is smaller than that of the dental product to be coated are advantageous. Coatings whose linear thermal expansion coefficients do not deviate from those of the substrate by more than ⁇ 3.0 ⁇ 10 -6 K -1 are particularly advantageous.
  • a coating is applied in particular by sintering, for example a glass, a glass ceramic or a composite.
  • sintering for example a glass, a glass ceramic or a composite.
  • the dental product containing lithium disilicate glass ceramic is brought into a temperature range which lies above the transformation point of the residual glass matrix of the glass ceramic.
  • Conventional lithium disilicate glass ceramics are often undesirably deformed because they have too little temperature stability.
  • the dental product according to the invention has an excellent temperature stability, for which in particular the content of La 2 O 3 and Al 2 O 3 in the stated amounts is responsible.
  • the glass ceramic according to the invention also has very good chemical resistance, which is caused by the use of Al 2 O 3 , La 2 O 3 , MgO and ZnO in the amounts specified.
  • Shaped dental products according to the invention that have a content have on the glass ceramic according to the invention come in particular Dental restorations, such as an inlay Onlay, a bridge, a pen structure, a facing, shells, Veneers, facets, connectors, a crown or a partial crown, in Question.
  • Dental restorations such as an inlay Onlay, a bridge, a pen structure, a facing, shells, Veneers, facets, connectors, a crown or a partial crown, in Question.
  • This example describes the preparation of an inventive Glass ceramics and their use as scaffolding material for the production of an individually formable all-ceramic Product, e.g. a crown or a multi-unit bridge, on which in addition a customized dental sintered ceramic is burned up.
  • an individually formable all-ceramic Product e.g. a crown or a multi-unit bridge
  • a starting glass with the chemical composition given in Table I, Example 21, was produced.
  • a mixture of oxides, carbonates and phosphates was melted in a platinum / rhodium crucible at a temperature of 1500 to 1600 ° C during a homogenization time of one hour.
  • the glass melt was quenched in water, and the glass frit formed was dried and ground to an average grain size of 20 to 30 ⁇ m.
  • glass-coloring oxides namely CeO 2 , TiO 2 and Fe 2 O 3 , made it possible to dispense with coloring using colored bodies.
  • the colored glass powder was then removed using a uniaxial dry press at room temperature and at one Pressing pressure of 750 bar to cylindrical starting glass blanks, in hereinafter referred to as green compacts, with a mass of approx. 4 g pressed.
  • the green compacts were removed in a kiln under vacuum sintered glass ceramic according to the invention in the form of a blank.
  • the green compact was at 500 ° C for pre-burned an hour.
  • the blank was then densely sintered in a second sintering treatment at 850 ° C for 2 hours, with a heating rate of 30 ° C / min. was worked.
  • the blanks obtained had comparable optical properties, e.g. Translucency, staining and turbidity as usual dental ceramic sales products such as IPS Empress OI Blanks from IVOCLAR AG, Liechtenstein.
  • Sintered blanks were used to determine the biaxial strength in slices with a diameter of 12 mm and a thickness of 1.1 mm sawn.
  • the biaxial strength was determined with a test apparatus with three-point support (steel balls with a Diameter of 3.2 mm) with selective application of force via a stamp with a diameter of 1.6 mm according to ISO 6872-1995 E "Dental Ceramic".
  • the feed rate of the Load application was 0.5 mm / min.
  • the under these conditions determined biaxial strength was 261 ⁇ 31 MPa.
  • the glass-ceramic blanks obtained were finally pressed in the viscous state into the sample geometry desired for the respective test using the pressing method and pressing furnace according to EP-A-0 231 773.
  • the standby temperature of the press furnace was 700 ° C, the heating rate up to the press temperature 60 ° C / min., The press temperature 920 ° C, the holding time at the press temperature 10 min. and the pressure 5 bar.
  • the mold was cooled in air and the test specimens were removed from the mold by sandblasting with Al 2 O 3 powder and glass beads.
  • the samples obtained had the following properties:
  • the plastically deformed glass ceramic had translucent properties, which enable the dental technician to make full ceramics out of it Dental products such as Crowns or multi-unit To create bridges that visually meet the requirements of a natural one Tooth.
  • Dental products such as Crowns or multi-unit To create bridges that visually meet the requirements of a natural one Tooth.
  • the hot-pressed glass ceramic was tooth-colored in the base glass. The color intensity could thereby by the concentration of the coloring oxides or through the additional use of colored bodies be set specifically.
  • rods measuring 1.5 ⁇ 4.8 ⁇ 20 mm 3 were pressed, and these were ground on all sides with SiC wet abrasive paper (grain size 1000).
  • the bending strength was determined with a span of the test equipment of 15 mm and a feed speed of the load application of 0.5 mm / min. according to ISO 6872-1995 E "Dental ceramic".
  • the 3-point bending strength determined under these conditions was 341 ⁇ 98 MPa.
  • cylindrical samples with a diameter of 6 mm were used and a length of 20 mm.
  • the in the temperature range of Expansion coefficient determined for these samples at 100 to 500 ° C was 10.6 ⁇ m / mK.
  • rods measuring 1.5 ⁇ 4.8 ⁇ 20 mm 3 were pressed, and these were ground on all sides with SiC wet abrasive paper (grain size 1000).
  • the samples were notched on one side to a depth of 2.8 mm using a diamond cutting disc (0.1 mm thickness) and then examined for their 3-point bending strength.
  • the bending strength was determined with a span of the test equipment of 15 mm and a feed speed of the load application of 0.5 mm / min.
  • the K 1c value determined was 4.0 ⁇ 0.2 MPa ⁇ m.
  • This example describes the preparation of an inventive Glass ceramics and their use as scaffolding material for the production of an individually formable all-ceramic Product, such as a crown or a multi-unit bridge, on which in addition a customized dental sintered ceramic is burned up.
  • a starting glass with the one in Table I, Example 18, chemical composition specified To was a mixture of oxides, carbonates and phosphates in one Platinum / rhodium crucible at a temperature of 1500 to 1600 ° C melted during a homogenization time of one hour. The glass melt was quenched in water, and the one formed Glass frit was dried and to an average grain size of Ground 20 to 30 ⁇ m. The glass powder was made with commercially available Color bodies and fluorescent agents are added and homogenized.
  • the colored glass powder was then removed using a uniaxial dry press at room temperature and at one Press pressure of 750 bar to form cylindrical green compacts with a mass of about 4 g pressed.
  • the green compacts were placed in a kiln under vacuum to the glass ceramic according to the invention in the form of a Sintered blanks.
  • the green compact was added Pre-baked at 500 ° C for 20 minutes.
  • the blank is then subjected to a second sintering treatment at 850 ° C for 30 minutes, with a heating rate of 30 ° C / min. was worked.
  • the blank is like proceeded in Example 22.
  • the blanks obtained had comparable optical properties, such as translucency, staining and turbidity, as usual dental ceramic sales products, e.g. IPS Empress Dentin 24 Blanks from IVOCLAR AG, Liechtenstein.
  • the biaxial strength was 270 ⁇ 38 MPa.
  • the glass-ceramic blanks obtained were finally pressed in the viscous state into the sample geometry desired for the respective test using the pressing method and pressing furnace according to EP-A-0 231 773.
  • the standby temperature of the press furnace was 700 ° C, the heating rate up to the press temperature 60 ° C / min., The press temperature 920 ° C, the holding time at the press temperature 10 min. and the pressure 5 bar.
  • the mold was cooled in air and the test specimens were removed from the mold by sandblasting with Al 2 O 3 powder and glass beads.
  • the plastically deformed glass ceramic had translucent properties, which enable the dental technician to make all-ceramic out of it Dental products such as Crowns or multi-unit To create bridges that visually meet the requirements of a natural one Tooth.
  • Dental products such as Crowns or multi-unit To create bridges that visually meet the requirements of a natural one Tooth.
  • the 3-point bending strength was 347 ⁇ 37 MPa.
  • the coefficient of expansion determined in the temperature range from 100 to 500 ° C was 10.7 ⁇ m / mK.
  • the K 1c value determined was 3.8 ⁇ 0.5 MPa ⁇ m.
  • the area-related mass loss determined according to ISO 6872-1995 after 16 hours' storage in 4% by volume aqueous acetic acid solution was significantly below the standard value for dental ceramic materials of 2000 ⁇ g / cm 2 .

Abstract

Sinterable lithium di:silicate glass ceramic contains (in wt.%): 57.0-80.0 SiO2; 0-5.0 Al2O3; 0.1-6.0 La2O3; 0-5.0 (esp. 0.1-5.0) Mg; 0-8.0 ZnO; 0-13.5 K2O; 11.0-19.0 Li2O; 0-11.0 P2O5; 0-8.0 colourants; and 0-6.0 additives. Al2O3+La2O3 = 0.1-7.0 wt.% and MgO+ZnO = 0.1-0.9 wt.%. The colourants comprise 0-5.0 wt.% glass-colouring oxides, and 0-5.0 wt.% coloured body. Also claimed is a process for forming a moulded dental product made of the glass ceramic.

Description

Die Erfindung betrifft sinterbare Lithiumdisilikat-Glaskeramiken und insbesondere solche, die sich aufgrund ihrer Eigenschaften zur Herstellung von geformten Dentalprodukten durch plastische verformung unter Druck- und Wärmeeinwirkung eignen.The invention relates to sinterable lithium disilicate glass ceramics and especially those that differ due to their properties for the production of molded dental products by plastic deformation under the influence of pressure and heat.

Lithiumdisilikat-Glaskeramiken sind aus dem Stand der Technik bekannt. So werden in der EP-B-536 479 selbstglasierte Lithiumdisilikat-Glaskeramikgegenstände beschrieben, die jedoch nicht für dentale Anwendungen vorgesehen sind. Die Glaskeramiken sind frei von La2O3 und werden in herkömmlicher Weise durch Erschmelzen geeigneter Ausgangsmaterialien, Eingießen in Formen und anschließende Wärmebehandlung der erhaltenen Gegenstände gebildet.Lithium disilicate glass ceramics are known from the prior art. For example, EP-B-536 479 describes self-glazed lithium disilicate glass ceramic articles, but these are not intended for dental applications. The glass ceramics are free of La 2 O 3 and are formed in a conventional manner by melting suitable starting materials, pouring them into molds and then heat treating the objects obtained.

Auch in der EP-B-536 572 sind Lithiumsilikat-Glaskeramiken offenbart. Durch Aufstreuen eines feinteiligen gefärbten Glases auf ihre Oberfläche erhalten sie Struktur und Färbung, und sie werden als Auskleidungselemente für Bauzwecke eingesetzt. Bei ihrer Herstellung wird in konventioneller Weise vorgegangen, indem geeignete Ausgangsmaterialien erschmolzen, die Schmelze zu einem gewünschten Körper geformt und der Körper zusammen mit aufgestreutem gefärbten Glas wärmebehandelt wird. La2O3 ist in der Glaskeramik jedoch nicht enthalten.Lithium-silicate glass ceramics are also disclosed in EP-B-536 572. By sprinkling a finely divided colored glass on their surface, they are given structure and color, and they are used as lining elements for building purposes. They are manufactured in a conventional manner by melting suitable starting materials, shaping the melt into a desired body and heat-treating the body together with scattered colored glass. However, La 2 O 3 is not included in the glass ceramic.

Aus der DE-C-1 421 886 sind Glaskeramiken auf der Basis von SiO2 und Li2O bekannt, welche große Mengen an physiologisch sehr bedenklichem Arsenoxid enthalten.From DE-C-1 421 886, glass ceramics based on SiO 2 and Li 2 O are known, which contain large amounts of arsenic oxide, which is physiologically very questionable.

Weiter wird im Stand der Technik auch die Verwendung von Lithiumdisilikat-Glaskeramiken in der Dentaltechnik offenbart, wobei diese Glaskeramiken jedoch alle keinerlei La2O3 oder MgO enthalten und zu ihrer Verarbeitung zu Dentalprodukten lediglich konventionelle Verfahren eingesetzt werden, bei denen eine Wärmebehandlung zur Ausscheidung von Kristallen nur an homogenen Körpern, nämlich aus einer Glasschmelze geformten Monolithen, wie kleinen Glasblöcken oder -plättchen, durchgeführt wird. Derartige konventionelle Verfahren gestatten jedoch nur, daß eine Volumenkristallisation, nicht jedoch eine Oberflächenkristallisation erfolgt.The state of the art also discloses the use of lithium disilicate glass ceramics in dental technology, but these glass ceramics all contain no La 2 O 3 or MgO and only conventional methods are used for their processing into dental products, in which a heat treatment to eliminate Crystals only on homogeneous bodies, namely monoliths formed from a glass melt, such as small glass blocks or platelets. However, such conventional methods only allow bulk crystallization, but not surface crystallization.

Beispiele für solche Glaskeramiken und konventionelle Verfahren zu ihrer Herstellung gehen aus den folgenden Dokumenten hervor.Examples of such glass ceramics and conventional processes the following documents show how to make them.

In US-A-4,515,634 wird eine zur Herstellung von Dentalkronen und -brücken geeignete Lithiumdisilikat-Glaskeramik hoher Festigkeit beschrieben.In US-A-4,515,634 one for the production of dental crowns and -bridging suitable lithium disilicate glass ceramic with high strength described.

Eine hochfeste Lithiumdisilikat-Glaskeramik beschreibt ebenfalls US-A-4,189,325, wobei diese Glaskeramik zwingend CaO zur Fließverbesserung sowie Platin und Nioboxid zur Erzeugung von sehr feinen und einheitlichen Kristallen enthält.A high-strength lithium disilicate glass ceramic also describes US-A-4,189,325, this glass ceramic being required for CaO Flow improvement as well as platinum and niobium oxide for the production of contains very fine and uniform crystals.

In FR-A-2 655 264 sind Lithiumoxid und Siliciumoxid enthaltende Glaskeramiken zur Herstellung von Dentalprothesen beschrieben, welche sehr große Mengen an MgO enthalten. FR-A-2 655 264 contains lithium oxide and silicon oxide Glass ceramics for the production of dental prostheses are described, which contain very large amounts of MgO.

Schließlich beschreiben US-A-5,507,981 und WO-A-95/32678 Lithiumdisilikat-Glaskeramiken, die durch spezielle Verfahren zu geformten Dentalprodukten weiterverarbeitet werden können, bei welchen ein Verpressen im viskosen, fließfähigen Zustand bei erhöhten Temperaturen zu dem gewünschten Dentalprodukt erfolgt. Nähere Angaben zu der Herstellung der dabei eingesetzten Plättchen werden nicht gemacht. Auch wird bei der Erzeugung der Glaskeramik in konventioneller Weise vorgegangen, indem homogene Glaskörper, wie zum Beispiel Plättchen, wärmebehandelt werden. Nachteilig an diesen Verfahren ist es, daß sie infolge der Verwendung eines speziellen verpreßbaren Tiegels für einen Zahntechniker sehr aufwendig sind. Weiter werden die glaskeramischen Materialien so weit erhitzt, bis keine Kristalle mehr in dem geschmolzenen Material vorhanden sind, da sonst die Viskosität für das Verpressen zu dem gewünschten Dentalprodukt zu hoch ist. Demnach wird nicht eine Glaskeramik, sondern ein Glas verarbeitet.Finally, US-A-5,507,981 and WO-A-95/32678 describe Lithium disilicate glass ceramics made by special processes shaped dental products can be further processed at which compress in the viscous, flowable state elevated temperatures to the desired dental product. More information on the manufacture of the used Tiles are not made. Also, the generation of Glass ceramics are handled in a conventional manner by using homogeneous Vitreous bodies, such as platelets, are heat treated. A disadvantage of these methods is that they are due to the Use of a special compressible crucible for one Dental technicians are very expensive. The glass ceramic will continue Materials heated until no more crystals in the molten material are present, otherwise the viscosity too high for pressing to the desired dental product is. Accordingly, not a glass ceramic, but a glass processed.

Die bekannten Lithiumdisilikat-Glaskeramiken zeigen Unzulänglichkeiten, insbesondere wenn es darum geht, sie im plastischen Zustand zu geformten Dentalprodukten weiterzuverarbeiten. Für eine derartige Verarbeitung ist ihre Viskosität nicht optimal eingestellt, so daß ein kontrolliertes Fließen nicht möglich und die Reaktion mit der eingesetzten Einbettmasse unerwünscht hoch ist. Weiter haben konventionelle Glaskeramiken nur eine geringe Temperaturstandfestigkeit, so daß aus ihnen hergestellte Dentalrestaurationen nur unter Deformation mit einer aufgesinterten Glas- oder Glaskeramik-Schicht versehen werden können. Schließlich mangelt es konventionellen Lithiumdisilikat-Glaskeramiken häufig auch an der erforderlichen chemischen Stabilität für den Einsatz als Dentalmaterial, welches in der Mundhöhle permanent mit Fluiden unterschiedlichster Art umspült wird.The known lithium disilicate glass ceramics show shortcomings, especially when it comes to sculpting them Processing condition to shaped dental products. For Such viscosity processing is not optimal adjusted so that a controlled flow is not possible and the reaction with the investment used was undesirably high is. Furthermore, conventional glass ceramics have only a small one Temperature stability, so that made from them Dental restorations only under deformation with a sintered Glass or glass ceramic layer can be provided. Finally, there is a lack of conventional lithium disilicate glass ceramics often also in the required chemical stability for use as a dental material in the oral cavity is constantly flushed with a wide variety of fluids.

Der Erfindung liegt demgemäß die Aufgabe zugrunde, eine Lithiumdisilikat-Glaskeramik zur Verfügung zu stellen, die ein optimales Fließverhalten bei gleichzeitig geringer Reaktion mit der Einbettmasse bei Verpressen im plastischen Zustand zu Dentalprodukten zeigt, eine hohe Temperaturstandfestigkeit, insbesondere im Bereich von 700 bis 900°C, hat und eine ausgezeichnete chemische Stabilität aufweist.The invention is accordingly based on the object of a lithium disilicate glass ceramic to provide the optimal one Flow behavior with little reaction with the Investment material when pressed in the plastic state into dental products shows a high temperature stability, in particular in the range of 700 to 900 ° C, and has an excellent has chemical stability.

Diese Aufgabe wird durch die sinterbare Lithiumdisilikat-Glaskeramik nach den Ansprüchen 1 bis 6 gelöst.This task is achieved through the sinterable lithium disilicate glass ceramic solved according to claims 1 to 6.

Gegenstand der Erfindung sind ebenfalls das Verfahren zur Herstellung von geformten Dentalprodukten nach den Ansprüchen 7 bis 13, die Verwendung der Glaskeramik nach Anspruch 14, geformte Dentalprodukte mit Gehalt an der Glaskeramik nach den Ansprüchen 15 und 16, sowie das Glas nach Anspruch 17.The invention also relates to the method for Production of shaped dental products according to claims 7 to 13, the use of the glass ceramic according to claim 14, shaped dental products containing glass ceramic according to the Claims 15 and 16, and the glass according to claim 17.

Die erfindungsgemäße sinterbare Lithiumdisilikat-Glaskeramik ist dadurch gekennzeichnet, daß sie die folgenden Komponenten enthält: Komponente Gew.-% SiO2 57,0 bis 80,0 Al2O3 0 bis 5,0 La2O3 0,1 bis 6,0 MgO 0 bis 5,0, insbesondere 0,1 bis 5,0 ZnO 0 bis 8,0 K2O 0 bis 13,5 Li2O 11,0 bis 19,0 P2O5 0 bis 11,0 Farbkomponenten 0 bis 8,0 Zusatzkomponenten 0 bis 6,0 wobei (a) Al2O3 + La2O3 0,1 bis 7,0 Gew.-% und (b) MgO + ZnO 0,1 bis 9,0 Gew.-% ausmachen und wobei die Farbkomponenten aus glasfärbenden Oxiden (c) und/oder Farbkörpern (d) in den folgenden Mengen gebildet sind: (c) glasfärbende Oxide 0 bis 5,0 Gew.-% und (d) Farbkörper 0 bis 5,0 Gew.-%. The sinterable lithium disilicate glass ceramic according to the invention is characterized in that it contains the following components: component % By weight SiO 2 57.0 to 80.0 Al 2 O 3 0 to 5.0 La 2 O 3 0.1 to 6.0 MgO 0 to 5.0, especially 0.1 to 5.0 ZnO 0 to 8.0 K 2 O 0 to 13.5 Li 2 O 11.0 to 19.0 P 2 O 5 0 to 11.0 Color components 0 to 8.0 Additional components 0 to 6.0 in which (a) Al 2 O 3 + La 2 O 3 0.1 to 7.0% by weight and (b) MgO + ZnO 0.1 to 9.0% by weight make up and the color components of glass-coloring oxides (c) and / or color bodies (d) are formed in the following amounts: (c) glass coloring oxides 0 to 5.0% by weight and (d) Color bodies 0 to 5.0% by weight.

Vorzugsweise besteht die Glaskeramik im wesentlichen aus den zuvor genannten Komponenten.The glass ceramic preferably consists essentially of the previously mentioned components.

Durch Röntgenbeugungsuntersuchungen konnte Lithiumdisilikat als Hauptkristallphase der erfindungsgemäßen Glaskeramik nachgewiesen werden.X-ray diffraction studies have shown that lithium disilicate Main crystal phase of the glass ceramic according to the invention detected become.

Für die einzelnen Komponenten der erfindungsgemäßen Lithiumdisilikat-Glaskeramik existieren bevorzugte Mengenbereiche. Diese können unabhängig voneinander gewählt werden und sind wie folgt: Komponente Gew.-% SiO2 57,0 bis 75,0 Al2O3 0 bis 2,5 La2O3 0,1 bis 4,0 MgO 0,1 bis 4,0 ZnO 0 bis 6,0, insbesondere 0,1 bis 5,0 K2O 0 bis 9,0, insbesondere 0,5 bis 7,0 Li2O 13,0 bis 19,0 P2O5 0 bis 8,0, insbesondere 0,5 bis 8,0 Farbkomponenten 0,05 bis 6,0 Zusatzkomponenten 0 bis 3,0. Preferred quantity ranges exist for the individual components of the lithium disilicate glass ceramic according to the invention. These can be selected independently of one another and are as follows: component % By weight SiO 2 57.0 to 75.0 Al 2 O 3 0 to 2.5 La 2 O 3 0.1 to 4.0 MgO 0.1 to 4.0 ZnO 0 to 6.0, especially 0.1 to 5.0 K 2 O 0 to 9.0, in particular 0.5 to 7.0 Li 2 O 13.0 to 19.0 P 2 O 5 0 to 8.0, in particular 0.5 to 8.0 Color components 0.05 to 6.0 Additional components 0 to 3.0.

Die erfindungsgemäße Glaskeramik enthält vorzugsweise Farbkomponenten, nämlich glasfärbende Oxide (c) und/oder Farbkörper (d), um eine farbliche Anpassung eines aus der Glaskeramik hergestellten Dentalproduktes an das natürliche Zahnmaterial des Patienten zu erzielen. Dabei sorgen die glasfärbenden Oxide, insbesondere TiO2, CeO2 und/oder Fe2O3, lediglich zum Erhalt einer Farbtönung, wobei die Hauptfärbung durch die Farbkörper hervorgerufen wird. Hierbei ist zu beachten, daß TiO2 nicht als Keimbildner, sondern in Kombination mit den anderen Oxiden als Farbkomponente wirkt. Als Farbkörper finden bei dentalen Glaskeramiken übliche Metalloxide und insbesondere handelsübliche isochrome Farbkörper, wie z.B. dotierte Spinelle und/oder dotiertes ZrO2, Anwendung. Bei den Farbkörpern kann es sich sowohl um nicht-fluoreszierende als auch fluoreszierende Materialien handeln.The glass ceramic according to the invention preferably contains color components, namely glass-coloring oxides (c) and / or color bodies (d), in order to achieve a color adaptation of a dental product made from the glass ceramic to the natural tooth material of the patient. The glass-coloring oxides, in particular TiO 2 , CeO 2 and / or Fe 2 O 3 , merely provide a color tint, the main color being caused by the color bodies. It should be noted here that TiO 2 does not act as a nucleating agent, but in combination with the other oxides as a color component. In the case of dental glass ceramics, the metal bodies used are customary metal oxides and in particular commercially available isochromic color bodies, such as, for example, doped spinels and / or doped ZrO 2 . The colored bodies can be both non-fluorescent and fluorescent materials.

Neben den zuvor erwähnten Komponenten kann die erfindungsgemäße Lithiumdisilikat-Glaskeramik auch noch Zusatzkomponenten enthalten, wofür insbesondere B2O3, F, Na2O, ZrO2, BaO und/oder SrO in Frage kommen. Dabei kann mit B2O3 und F die Viskosität der Restglasphase der Glaskeramik beeinflußt werden und man nimmt an, daß sie das Verhältnis Oberflächen- zu Volumenkristallisation zugunsten der Oberflächenkristallisation verschieben.In addition to the components mentioned above, the lithium disilicate glass ceramic according to the invention can also contain additional components, for which B 2 O 3 , F, Na 2 O, ZrO 2 , BaO and / or SrO are particularly suitable. With B 2 O 3 and F the viscosity of the residual glass phase of the glass ceramic can be influenced and it is assumed that they shift the ratio of surface to volume crystallization in favor of surface crystallization.

Zur Herstellung der erfindungsgemäßen Glaskeramiken wird insbesondere das im folgenden näher beschriebene Verfahren zur Herstellung von geformten Dentalprodukten mit Gehalt an der Glaskeramik verwendet, wobei spezielle Formgebungen jedoch entfallen können.In particular, the glass ceramics according to the invention are produced the method described in more detail below Manufacture of molded dental products containing Glass ceramics are used, but special shapes can be omitted.

Das erfindungsgemäße Verfahren zur Herstellung von geformten Dentalprodukten mit Gehalt an der erfindungsgemäßen sinterbaren Lithiumdisilikat-Glaskeramik zeichnete sich dadurch aus, daß

  • (a) ein Ausgangsglas, welches die Komponenten gemäß einem der Ansprüche 1 bis 6 mit Ausnahme der Farbkörper enthält, bei Temperaturen von 1200 bis 1650°C erschmolzen wird,
  • (b) die Glasschmelze unter Bildung eines Glasgranulats in Wasser eingegossen wird,
  • (c) das Glasgranulat zu einem Pulver mit einer mittleren Korngröße von 1 bis 100 µm, bezogen auf die Teilchenzahl, zerkleinert wird,
  • (d) dem Pulver die ggf. vorhandenen Farbkörper zugesetzt werden,
  • (e) das Pulver zu einem Ausgangsglas-Rohling gewünschter Geometrie und heterogener Struktur dichtgepreßt wird, und
  • (f) der Ausgangsglas-Rohling im Vakuum und im Temperaturbereich von 400 bis 1100°C einer oder mehrerer Wärmebehandlungen unterzogen wird, um ein Dichtsintern zu bewirken und ein als Rohling vorliegendes Dentalprodukt zu bilden.
    • The inventive method for producing shaped dental products containing the sinterable lithium disilicate glass ceramic according to the invention was characterized in that
  • (a) an initial glass, which contains the components according to one of claims 1 to 6 with the exception of the colored bodies, is melted at temperatures of 1200 to 1650 ° C,
  • (b) the glass melt is poured into water to form a glass granulate,
  • (c) the glass granulate is ground to a powder with an average grain size of 1 to 100 μm, based on the number of particles,
  • (d) the color bodies which may be present are added to the powder,
  • (e) the powder is compacted into a starting glass blank of desired geometry and heterogeneous structure, and
  • (f) the starting glass blank is subjected to one or more heat treatments in a vacuum and in the temperature range from 400 to 1100 ° C. in order to effect a sealing sintering and to form a dental product as a blank.

    • Im Verfahrensschritt (a) wird ein Ausgangsglas erschmolzen, wozu geeignete Ausgangsmaterialien, wie zum Beispiel Carbonate, Oxide und Fluoride, innig miteinander vermischt und auf die angegebenen Temperaturen erwärmt werden, wodurch sich das Ausgangsglas bildet. Sofern farbgebende Oxide eingesetzt werden sollen, so werden diese dem Gemenge zugegeben. Die Zugabe von gegebenenfalls vorhandenen Farbkörpern erfolgt in einer späteren Stufe des Verfahrens, da ihre Wirkung bei den hohen in der Glasschmelze herrschenden Temperaturen verloren gehen würde.In process step (a), an initial glass is melted, for which purpose suitable starting materials, such as carbonates, oxides and fluorides, intimately mixed together and to the specified Temperatures are heated, causing the exit glass forms. If coloring oxides are to be used, see above these are added to the batch. The addition of if necessary existing color bodies take place in a later stage of Process because its effect at high in the glass melt prevailing temperatures would be lost.

    Sodann wird in Stufe (b) die erhaltene Glasschmelze durch Eingießen in Wasser abgeschreckt und dadurch zu einem Glasgranulat umgewandelt. Diese Vorgehensweise wird üblicherweise auch als Fritten bezeichnet.The glass melt obtained is then passed through in stage (b) Poured into water and quenched into a glass granulate converted. This procedure is common also known as fries.

    Anschließend wird das Glasgranulat in Stufe (c) zerkleinert und insbesondere mit üblichen Mühlen auf die gewünschte Korngröße gemahlen. Dabei ist eine mittlere Korngröße des erhaltenen Pulvers von 10 bis 50 µm, bezogen auf die Teilchenzahl, bevorzugt. The glass granulate is then crushed in step (c) and in particular with conventional mills to the desired grain size ground. Here is an average grain size of the obtained Powder of 10 to 50 microns, based on the number of particles, preferred.

    In Stufe (d) erfolgt dann die Zugabe von gegebenenfalls vorhandenen Farbkörpern.In step (d) the addition of any that are present is then carried out Color bodies.

    In Stufe (e) wird das Pulver danach zu einem Glasrohling gewünschter Geometrie und heterogener Struktur verdichtet, wobei Preßdrucke von insbesondere 500 bis 2.000 bar Anwendung finden und insbesondere bei Raumtemperatur gearbeitet wird. Dieser Verfahrensschritt des Pressens zu einem Rohling mit heterogener Struktur ist wichtig, damit im Gegensatz zu den aus dem Stand der Technik gekannten Verfahrensweisen bei der folgenden Wärmebehandlung in Stufe (f) neben einer Volumenkristallisation auch eine Oberflächenkristallisation erfolgen kann. So ermöglicht die heterogene Struktur des aus zusammengepreßten Ausgangsglaspulverteilchen bestehenden Ausgangsglas-Rohlings eine gesteuerte Oberflächenkristallisation an den inneren Oberflächen des Glaspulvers. Diese Oberflächenkristallisation ist daran erkennbar, daß auch ohne übliche Volumenkeimbildner, wie zum Beispiel Metalle oder P2O5, die in Stufe (f) erfolgende Wärmebehandlung zur Bildung einer fein verteilte Kristalle enthaltenden Lithiumdisilikat-Glaskeramik führt. Bei Verwendung von P2O5 als Komponente des Ausgangsglases führt die Wärmebehandlung in Stufe (f) dazu, daß sowohl eine Oberflächenkristallisation als auch eine Volumenkristallisation erfolgt. Bei konventionellen Verfahren werden hingegen Rohlinge eingesetzt, die eine homogene Struktur aufweisen, d.h. bei denen keine Ausgangsglaspulverteilchen vorliegen. Das führt dazu, daß eine Oberflächenkristallisation nicht möglich ist.In step (e), the powder is then compacted into a glass blank of the desired geometry and heterogeneous structure, with pressures of in particular 500 to 2,000 bar being used and in particular being carried out at room temperature. This process step of pressing into a blank with a heterogeneous structure is important so that, in contrast to the methods known from the prior art, in the subsequent heat treatment in step (f), surface crystallization can also take place in addition to volume crystallization. The heterogeneous structure of the starting glass blank consisting of compressed starting glass powder particles enables controlled surface crystallization on the inner surfaces of the glass powder. This surface crystallization can be recognized from the fact that even without conventional bulk nucleating agents, such as metals or P 2 O 5 , the heat treatment carried out in stage (f) leads to the formation of a lithium disilicate glass ceramic containing finely divided crystals. If P 2 O 5 is used as a component of the starting glass, the heat treatment in stage (f) leads to both surface crystallization and bulk crystallization. In contrast, conventional processes use blanks which have a homogeneous structure, ie in which there are no starting glass powder particles. This means that surface crystallization is not possible.

    Die in Stufe (f) erfolgende Wärmebehandlung dient zu Auslösung der Kristallisation des Ausgangsglas-Rohlings und damit zur Bildung der Glaskeramik, die nach Abschluß dieser Verfahrensstufe als dichtgesinterter glaskeramischer Rohling vorliegt. Dieser Rohling hat üblicherweise die Form eines kleinen Zylinders oder eines kleinen Plättchens. The heat treatment in stage (f) is used for triggering the crystallization of the starting glass blank and thus for Formation of the glass ceramic after the completion of this process step is a densely sintered glass ceramic blank. This Blank usually has the shape of a small cylinder or a small tile.

    Zur Erzeugung des endgültigen Dentalproduktes, wie einer Brücke oder einer Krone, bestehen insbesondere die folgenden zwei Möglichkeiten (g1) oder (g2).To create the final dental product, such as a bridge or a crown, there are in particular the following two Possibilities (g1) or (g2).

    Zum einen wird in Stufe (g1) das als Rohling vorliegende Dentalprodukt bei einer Temperatur von 700 bis 1200°C und durch Anwendung von Druck von 2 bis 10 bar zu einem Dentalprodukt gewünschter Geometrie plastisch verformt. Hierzu werden insbesondere das in der EP-A-231 773 beschriebene Verfahren sowie der dort offenbarte Preßofen benutzt. Bei diesem Verfahren wird der Rohling im plastischen Zustand in einen dem gewünschten geformten Dentalprodukt entsprechenden Formhohlraum eingepreßt. Der hierfür eingesetzte Preßofen wird als Empress®-Ofen von der Ivoclar AG, Liechtenstein, vertrieben.On the one hand, in step (g1) the present as a blank Dental product at a temperature of 700 to 1200 ° C and through Application of pressure from 2 to 10 bar to a dental product desired geometry plastically deformed. For this, in particular the method described in EP-A-231 773 and the press furnace disclosed there is used. With this procedure the blank in the plastic state in one of the desired molded dental product corresponding mold cavity. The press furnace used for this is the Empress® furnace from Ivoclar AG, Liechtenstein.

    Es wurde festgestellt, daß konventionelle Lithiumdisilikat-Glaskeramiken verschiedenen Anforderungen für eine Weiterverarbeitung zu Dentalprodukten durch plastische Verformung nicht genügen. So ist es für diese Weiterverarbeitung erforderlich, daß der im plastischen Zustand befindliche Rohling in kontrollierter Weise fließt und gleichzeitig nur in geringem Maße mit der Einbettmasse reagiert. Diese beiden Eigenschaften werden bei der erfindungsgemäßen Glaskeramik überraschenderweise durch den Einsatz von La2O3 und Al2O3 in den angegebenen Mengen erzielt. Daher ist es sehr erstaunlich, daß das als Rohling vorliegende Dentalprodukt fließfähig und im plastischen Zustand verpreßbar ist, obwohl es bereits ein glaskeramisches Material darstellt. Nach dem Stand der Technik werden hingegen stets Gläser als flüssige Schmelze eingesetzt, da sonst ein Verpressen im plastischen Zustand aufgrund zu hoher Viskosität nicht möglich ist.It was found that conventional lithium disilicate glass ceramics do not meet various requirements for further processing into dental products by plastic deformation. It is necessary for this further processing that the blank, which is in the plastic state, flows in a controlled manner and at the same time reacts only to a small extent with the investment material. In the glass ceramic according to the invention, these two properties are surprisingly achieved by using La 2 O 3 and Al 2 O 3 in the amounts specified. It is therefore very surprising that the dental product in the form of a blank is flowable and compressible in the plastic state, even though it is already a glass-ceramic material. According to the state of the art, however, glasses are always used as a liquid melt, since otherwise compression in the plastic state is not possible due to the high viscosity.

    Es hat sich als besonders vorteilhaft herausgestellt, wenn das als Rohling vorliegende Dentalprodukt eine Viskosität von 105 bis 106 Pa·s bei der plastischen Verformung in Stufe (g1) aufweist. It has turned out to be particularly advantageous if the dental product in the form of a blank has a viscosity of 10 5 to 10 6 Pa · s during plastic deformation in stage (g1).

    Weiter kann das als Rohling vorliegende Dentalprodukt auch in Stufe (g2) maschinell zu einem Dentalprodukt gewünschter Geometrie verarbeitet werden, wozu insbesondere computergestützte Fräsmaschinen eingesetzt werden.Furthermore, the dental product present as a blank can also be used in Step (g2) mechanically desired to a dental product Geometry are processed, especially computer-aided Milling machines are used.

    In vielen Fällen ist es vorteilhaft, daß das nach Stufe (g1) oder (g2) erhaltene Dentalprodukt gewünschter Geometrie noch in Stufe (h) mit einer Beschichtung versehen wird. Als Beschichtung kommen dabei insbesondere ein Keramik, eine Sinterkeramik, eine Glaskeramik, ein Glas, eine Glasur und/oder ein Composit in Frage. Vorteilhaft sind solche Beschichtungen, die eine Sintertemperatur von 650 bis 950°C und einen linearen thermischen Ausdehnungkoeffizienten haben, welcher kleiner ist als der des zu beschichtenden Dentalproduktes. Besonders vorteilhaft sind Beschichtungen, deren lineare thermische Ausdehnungskoeffizienten nicht mehr als ± 3,0·10-6K-1 von denen des Substrats abweichen.In many cases it is advantageous that the dental product of the desired geometry obtained after step (g1) or (g2) is provided with a coating in step (h). A ceramic, a sintered ceramic, a glass ceramic, a glass, a glaze and / or a composite are particularly suitable as coatings. Coatings which have a sintering temperature of 650 to 950 ° C. and a linear coefficient of thermal expansion which is smaller than that of the dental product to be coated are advantageous. Coatings whose linear thermal expansion coefficients do not deviate from those of the substrate by more than ± 3.0 · 10 -6 K -1 are particularly advantageous.

    Die Aufbringung einer Beschichtung erfolgt insbesondere durch Aufsinterung, zum Beispiel eines Glases, einer Glaskeramik oder eines Composites. Während dieses Sintervorganges wird das Lithiumdisilikat-Glaskeramik enthaltende Dentalprodukt allerdings in einen Temperaturbereich gebracht, der oberhalb des Transformationspunktes der Restglasmatrix der Glaskeramik liegt. Konventionelle Lithiumdisilikat-Glaskeramiken werden hierbei häufig in unerwünschten Weise deformiert, da sie eine zu geringe Temperaturstandfestigkeit haben. Das erfindungsgemäße Dentalprodukt hat jedoch eine ausgezeichnete Temperaturstandfestigkeit, wofür insbesondere der Gehalt an La2O3 und Al2O3 in den angegebenen Mengen verantwortlich ist.A coating is applied in particular by sintering, for example a glass, a glass ceramic or a composite. During this sintering process, however, the dental product containing lithium disilicate glass ceramic is brought into a temperature range which lies above the transformation point of the residual glass matrix of the glass ceramic. Conventional lithium disilicate glass ceramics are often undesirably deformed because they have too little temperature stability. However, the dental product according to the invention has an excellent temperature stability, for which in particular the content of La 2 O 3 and Al 2 O 3 in the stated amounts is responsible.

    Neben einer Aufsinterung können auch andere Verfahren angewendet werden, wie sie zum Herstellen von Werkstoffverbunden üblich sind, wie z.B. Kleben oder Löten.In addition to sintering, other methods can also be used as usual for the production of composite materials are, e.g. Glue or solder.

    Weiter zeigt die erfindungsgemäße Glaskeramik auch eine sehr gute chemische Beständigkeit, was durch den Einsatz von Al2O3, La2O3, MgO und ZnO in den angegebenen Mengen hervorgerufen wird. Furthermore, the glass ceramic according to the invention also has very good chemical resistance, which is caused by the use of Al 2 O 3 , La 2 O 3 , MgO and ZnO in the amounts specified.

    Neben den zuvor erwähnten Eigenschaften der erfindungsgemäßen Lithiumdisilikat-Glaskeramiken haben diese noch die folgenden weiteren wesentlichen Eigenschaften, durch die sie sich besonders zur Verwendung als Dentalmaterial oder Komponente davon eignen:

    • Hohe Biegebruchfestigkeiten von 200 bis 400 MPa. Das Meßverfahren ist in den Beispielen erläutert.
    • Hohe Bruchzähigkeiten von 3 bis 4,5 MPa·m1/2. Das Bestimmungsverfahren ist in den Beispielen erläutert.
    • Eine mit der des natürlichen Zahnes vergleichbare Transluzenz, obwohl die Erzeugung der erfindungsgemäßen Glaskeramik zumindest teilweise nach dem Mechanismus der Oberflächenkristallisation erfolgt. Das ist deshalb überraschend, da durch Oberflächenkristallisationseffekte oder Initierung der Oberflächenkeimbildung, wie im Falle der Bildung von Oberflächenverspannung durch β-Quarz-Mischkristallbildung, bei anderen Glaskeramiksystemen häufig eine Trübung hervorgerufen wird.
    • Anpaßbarkeit der Farbe an die eines natürlichen Zahnes durch Verwendung von Farbkomponenten. Dabei ist erstaunlich, daß trotz der einsetzbaren Farbkomponenten die Festigkeit und Zähigkeit der Glaskeramik nicht nachteilig beeinflußt wird. So ist beispielsweise bei Leucit-Glaskeramiken, die ebenfalls nach dem Mechanismus der Oberflächenkristallisation erzeugt werden, bekannt, daß durch derartige Zusätze die Kristallisation stark beeinflußt und die Festigkeit häufig sehr verringert wird.
    • Gute Ätzbarkeit der Glaskeramik, wenn diese als Dentalrestauration eingesetzt wird. Dabei wird zum Beispiel auf der Innenseite einer erfindungsgemäßen Dentalkrone durch kontrolliertes Ätzen ein retentives Muster erzeugt. Bei einem retentiven Muster erfolgt kein flächiger Abtrag der Glaskeramik, wie es zum Beispiel bei Glimmerglaskeramiken der Fall ist, sondern es werden im Oberflächenbereich kleine offenporige Gefüge erzeugt. Durch ein derartiges retentives Muster wird es möglich, daß die Glaskeramik mit Hilfe eines adhäsiven Klebesystemes auf dem natürlichen Zahn befestigt werden kann.
    In addition to the previously mentioned properties of the lithium disilicate glass ceramics according to the invention, they also have the following further essential properties which make them particularly suitable for use as a dental material or component thereof:
    • High flexural strength from 200 to 400 MPa. The measuring method is explained in the examples.
    • High fracture toughness from 3 to 4.5 MPa · m 1/2 . The determination method is explained in the examples.
    • A translucency comparable to that of natural teeth, although the glass ceramic according to the invention is produced at least in part by the mechanism of surface crystallization. This is surprising because surface crystallization effects or the initiation of surface nucleation, as in the case of the formation of surface tension by the formation of β-quartz mixed crystals, often cause clouding in other glass ceramic systems.
    • Adaptability of the shade to that of a natural tooth by using shade components. It is astonishing that, despite the color components that can be used, the strength and toughness of the glass ceramic are not adversely affected. For example, in the case of leucite glass ceramics, which are also produced by the mechanism of surface crystallization, it is known that such additives have a strong influence on the crystallization and the strength is often very greatly reduced.
    • Good etchability of the glass ceramic when used as a dental restoration. For example, a retentive pattern is generated on the inside of a dental crown according to the invention by controlled etching. In the case of a retentive pattern, there is no surface removal of the glass ceramic, as is the case, for example, with mica glass ceramics, but small open-pore structures are produced in the surface area. Such a retentive pattern makes it possible for the glass ceramic to be attached to the natural tooth with the aid of an adhesive adhesive system.

    Als erfindungsgemäße geformte Dentalprodukte, die einen Gehalt an der erfindungsgemäßen Glaskeramik aufweisen, kommen insbesondere Dentalrestaurationen, wie zum Beispiel ein Inlay, ein Onlay, eine Brücke, ein Stiftaufbau, eine Verblendung, Schalen, Veneers, Facetten, Verbinder, eine Krone oder eine Teilkrone, in Frage.Shaped dental products according to the invention that have a content have on the glass ceramic according to the invention come in particular Dental restorations, such as an inlay Onlay, a bridge, a pen structure, a facing, shells, Veneers, facets, connectors, a crown or a partial crown, in Question.

    Die Erfindung wird nachstehend anhand von Beispielen näher erläutert.The invention is illustrated below with the aid of examples explained.

    BeispieleExamples Beispiele 1 bis 21Examples 1 to 21

    Es wurden insgesamt 21 verschiedene erfindungsgemäße Glaskeramiken und geformte Dentalprodukte mit der in Tabelle I angegebenen chemischen Zusammensetzung hergestellt, indem die Stufen (a) bis (f) des beschriebenen Verfahrens durchgeführt wurden.

    Figure 00130001
    Figure 00140001
    A total of 21 different glass ceramics and shaped dental products according to the invention were produced with the chemical composition given in Table I by carrying out steps (a) to (f) of the process described.
    Figure 00130001
    Figure 00140001

    Beispiel 22Example 22

    Dieses Beispiel beschreibt die Herstellung einer erfindungsgemäßen Glaskeramik und deren Einsatzmöglichkeit als Gerüstmaterial zur Herstellung eines individuell formbaren vollkeramischen Produktes, wie z.B. eine Krone oder einer mehrgliedrigen Brücke, auf welches zusätzlich eine angepaßte Dentalsinterkeramik aufgebrannt wird.This example describes the preparation of an inventive Glass ceramics and their use as scaffolding material for the production of an individually formable all-ceramic Product, e.g. a crown or a multi-unit bridge, on which in addition a customized dental sintered ceramic is burned up.

    Zunächst wurde ein Ausgangsglas mit der in Tabelle I, Beispiel 21, angegebenen chemischen Zusammensetzung hergestellt. Dazu wurde ein Gemenge aus Oxiden, Carbonaten und Phosphaten in einem Platin/Rhodium-Tiegel bei einer Temperatur von 1500 bis 1600°C während einer Homogenisierungszeit von einer Stunde erschmolzen. Die Glasschmelze wurde in Wasser abgeschreckt, und die gebildete Glasfritte wurde getrocknet und auf eine mittlere Korngröße von 20 bis 30 µm gemahlen. Durch den Einsatz von glasfärbenden Oxiden, nämlich CeO2, TiO2 und Fe2O3, konnte auf eine Farbgebung durch Farbkörper verzichtet werden.First, a starting glass with the chemical composition given in Table I, Example 21, was produced. For this purpose, a mixture of oxides, carbonates and phosphates was melted in a platinum / rhodium crucible at a temperature of 1500 to 1600 ° C during a homogenization time of one hour. The glass melt was quenched in water, and the glass frit formed was dried and ground to an average grain size of 20 to 30 μm. The use of glass-coloring oxides, namely CeO 2 , TiO 2 and Fe 2 O 3 , made it possible to dispense with coloring using colored bodies.

    Anschließend wurde das eingefärbte Glaspulver mittels einer uniaxialen Trockenpresse bei Raumtemperatur und bei einem Preßdruck von 750 bar zu zylindrischen Ausgangsglasrohlingen, im folgenden als Grünlinge bezeichnet, mit einer Masse von ca. 4 g gepreßt. Die Grünlinge wurden in einem Brennofen unter Vakuum zur erfindungsgemäßen Glaskeramik in Form eines Rohlinges gesintert. In einer ersten Phase wurde der Grünling dazu bei 500°C während einer Stunde vorgebrannt. Dichtgesintert wurde der Rohling dann in einer zweiten Sinterbehandlung bei 850°C während 2 Stunden, wobei mit einer Aufheizrate von 30°C/min. gearbeitet wurde. The colored glass powder was then removed using a uniaxial dry press at room temperature and at one Pressing pressure of 750 bar to cylindrical starting glass blanks, in hereinafter referred to as green compacts, with a mass of approx. 4 g pressed. The green compacts were removed in a kiln under vacuum sintered glass ceramic according to the invention in the form of a blank. In a first phase, the green compact was at 500 ° C for pre-burned an hour. The blank was then densely sintered in a second sintering treatment at 850 ° C for 2 hours, with a heating rate of 30 ° C / min. was worked.

    RohlingeigenschaftenBlank properties Optische EigenschaftenOptical properties

    Die erhaltenen Rohlinge wiesen vergleichbare optische Eigenschaften, z.B. Transluzenz, Färbung und Trübung, wie übliche dentalkeramische Verkaufprodukte, wie z.B. IPS Empress OI Rohlinge von IVOCLAR AG, Liechtenstein, auf.The blanks obtained had comparable optical properties, e.g. Translucency, staining and turbidity as usual dental ceramic sales products such as IPS Empress OI Blanks from IVOCLAR AG, Liechtenstein.

    BiaxialfestigkeitBiaxial strength

    Zur Bestimmung der Biaxialfestigkeit wurden gesinterte Rohlinge in Scheiben mit einem Durchmesser von 12 mm und einer Dicke von 1,1 mm zersägt. Die Ermittlung der Biaxialfestigkeit erfolgte mit einer Prüfapparatur mit Dreipunktauflage (Stahlkugeln mit einem Durchmesser von 3,2 mm) mit punktueller Krafteinleitung über einen Stempel mit einem Durchmesser von 1,6 mm gemäß ISO 6872-1995 E "Dental Ceramic". Die Vorschubgeschwindigkeit der Lastaufbringung betrug 0,5 mm/min. Die unter diesen Bedingungen ermittelte Biaxialfestigkeit war 261 ± 31 MPa.Sintered blanks were used to determine the biaxial strength in slices with a diameter of 12 mm and a thickness of 1.1 mm sawn. The biaxial strength was determined with a test apparatus with three-point support (steel balls with a Diameter of 3.2 mm) with selective application of force via a stamp with a diameter of 1.6 mm according to ISO 6872-1995 E "Dental Ceramic". The feed rate of the Load application was 0.5 mm / min. The under these conditions determined biaxial strength was 261 ± 31 MPa.

    Die erhaltenen glaskeramischen Rohlinge wurden schließlich unter Verwendung des Preßverfahrens und Preßofens gemäß EP-A-0 231 773 unter Vakuum im viskosen Zustand in die für den jeweiligen Test gewünschte Probengeometrie verpreßt. Dabei betrugen die Bereitschaftstemperatur des Preßofens 700°C, die Heizrate bis zur Preßtemperatur 60°C/min., die Preßtemperatur 920°C, die Haltezeit bei der Preßtemperatur 10 min. und der Preßdruck 5 bar. Nach dem Preßvorgang wurde die Preßform an der Luft abgekühlt, und die Probenkörper wurden durch Sandstrahlen mit Al2O3-Pulver und Glasperlen entformt.The glass-ceramic blanks obtained were finally pressed in the viscous state into the sample geometry desired for the respective test using the pressing method and pressing furnace according to EP-A-0 231 773. The standby temperature of the press furnace was 700 ° C, the heating rate up to the press temperature 60 ° C / min., The press temperature 920 ° C, the holding time at the press temperature 10 min. and the pressure 5 bar. After the pressing process, the mold was cooled in air and the test specimens were removed from the mold by sandblasting with Al 2 O 3 powder and glass beads.

    Die erhaltenen Proben hatten folgende Eigenschaften: The samples obtained had the following properties:

    Eigenschaften plastisch verformter GlaskeramikProperties of plastically deformed glass ceramics Optische EigenschaftenOptical properties

    Die plastisch verformte Glaskeramik hatte transluzente Eigenschaften, die es dem Zahntechniker ermöglichen, aus ihr vollkermaische Dentalprodukte, wie z.B. Kronen oder mehrgliedrige Brücken herzustellen, die optisch den Vorgaben eines natürlichen Zahnes entsprechen. Durch den Einsatz von glasfärbenden Oxiden im Grundglas war die heißgepreßte Glaskeramik zahnfarben getönt. Die Farbintensität konnte dabei durch die Konzentration der färbenden Oxide oder durch den zusätzlichen Einsatz von Farbkörpern gezielt eingestellt werden.The plastically deformed glass ceramic had translucent properties, which enable the dental technician to make full ceramics out of it Dental products such as Crowns or multi-unit To create bridges that visually meet the requirements of a natural one Tooth. Through the use of glass-coloring oxides the hot-pressed glass ceramic was tooth-colored in the base glass. The color intensity could thereby by the concentration of the coloring oxides or through the additional use of colored bodies be set specifically.

    Die Kombination von transluzentem Gerüstmaterial und transluzenter bis transparenter Dentalsinterglaskeramik mit einem Ausdehnungskoeffizienten von 9,1 µm/mK, die schichtweise auf das plastisch geformte Kronen- oder Brückengerüst bei 800°C unter Vakuum aufgesintert wurde, führte zu transluzenten, vollkeramischen Dentalrestaurationen, die den hohen ästhetischen Anforderungen an derartige Produkte genügen.The combination of translucent framework material and translucent to transparent dental sintered glass ceramic with one Expansion coefficients of 9.1 µm / mK, which in layers on the plastically shaped crown or bridge framework at 800 ° C below Vacuum sintering led to translucent, all-ceramic Dental restorations that meet the high aesthetic requirements of such products are sufficient.

    3-Punkt-Biegefestigkeit3-point bending strength

    Hierzu wurden Stäbe mit den Maßen 1,5 × 4,8 × 20 mm3 gepreßt, und diese wurden mit SiC-Naßschleifpapier (1000-er Körnung) allseitig überschliffen. Die Ermittlung de Biegefestigkeit erfolgte bei einer Stützweite des Prüfmittels von 15 mm und einer Vorschubgeschwindigkeit der Lastaufbringung von 0,5 mm/min. gemäß ISO 6872-1995 E "Dental ceramic". Die bei diesen Bedingungen ermittelte 3-Punkt-Biegefestigkeit betrug 341 ± 98 MPa. For this purpose, rods measuring 1.5 × 4.8 × 20 mm 3 were pressed, and these were ground on all sides with SiC wet abrasive paper (grain size 1000). The bending strength was determined with a span of the test equipment of 15 mm and a feed speed of the load application of 0.5 mm / min. according to ISO 6872-1995 E "Dental ceramic". The 3-point bending strength determined under these conditions was 341 ± 98 MPa.

    Linearer thermischer AusdehnungskoeffizientLinear coefficient of thermal expansion

    Hierzu wurden zylindrische Proben mit einem Durchmesser von 6 mm und einer Länge von 20 mm gepreßt. Der im Temperaturbereich von 100 bis 500°C für diese Proben bestimmte Ausdehnungskoeffizient betrug 10,6 µm/mK.For this purpose, cylindrical samples with a diameter of 6 mm were used and a length of 20 mm. The in the temperature range of Expansion coefficient determined for these samples at 100 to 500 ° C was 10.6 µm / mK.

    Bruchzähigkeit KFracture toughness K 1c1c

    Hierzu wurden Stäbe mit den Maßen 1,5 × 4,8 × 20 mm3 gepreßt, und diese wurden mit SiC-Naßschleifpapier (1000-er Körnung) allseitig überschliffen. Mit einer Diamanttrennscheibe (0,1 mm Dicke) wurden die Proben einseitig auf eine Tiefe von 2,8 mm gekerbt und anschließend auf ihre 3-Punkt-Biegefestigkeit untersucht. Die Ermittlung der Biegefestigkeit erfolgte bei einer Stützweite des Prüfmittels von 15 mm und einer Vorschubgeschwindigkeit der Lastaufbringung von 0,5 mm/min. Der ermittelte K1c-Wert betrug 4,0 ± 0,2 MPa √m.For this purpose, rods measuring 1.5 × 4.8 × 20 mm 3 were pressed, and these were ground on all sides with SiC wet abrasive paper (grain size 1000). The samples were notched on one side to a depth of 2.8 mm using a diamond cutting disc (0.1 mm thickness) and then examined for their 3-point bending strength. The bending strength was determined with a span of the test equipment of 15 mm and a feed speed of the load application of 0.5 mm / min. The K 1c value determined was 4.0 ± 0.2 MPa √m.

    SäurebeständigkeitAcid resistance

    Hierzu wurden scheibenförmige Proben mit einem Durchmesser von 15 mm und einer Dicke von 1,5 mm gepreßt und anschließend mit SiC-Naßschleifpapier (1000-er Körnung) allseitig überschliffen. Der gemäß ISO 6872-1995 E "Dental ceramic" bestimmte flächenbezogene Massenverlust dieser Proben wurde nach 16-stündiger Lagerung in 4 Vol.-%iger wäßriger Essigsäurelösung bestimmt, und er betrug lediglich 73 µg/cm2 und lag damit deutlich unter dem Normwert für Dentalkeramikmaterialien von 2000 µg/cm2.For this purpose, disk-shaped samples with a diameter of 15 mm and a thickness of 1.5 mm were pressed and then ground on all sides with SiC wet abrasive paper (1000 grit). The area-related mass loss of these samples, determined in accordance with ISO 6872-1995 E “Dental ceramic”, was determined after 16 hours of storage in 4% by volume aqueous acetic acid solution, and was only 73 µg / cm 2 and was therefore well below the standard value for Dental ceramic materials of 2000 µg / cm 2 .

    Beispiel 23Example 23

    Dieses Beispiel beschreibt die Herstellung einer erfindungsgemäßen Glaskeramik und deren Einsatzmöglichkeit als Gerüstmaterial zur Herstellung eines individuell formbaren vollkeramischen Produktes, wie z.B einer Krone oder einer mehrgliedrigen Brücke, auf welches zusätzlich eine angepaßte Dentalsinterkeramik aufgebrannt wird.This example describes the preparation of an inventive Glass ceramics and their use as scaffolding material for the production of an individually formable all-ceramic Product, such as a crown or a multi-unit bridge, on which in addition a customized dental sintered ceramic is burned up.

    Zunächst wurde ein Ausgangsglas mit der in Tabelle I, Beispiel 18, angegebenen chemischen Zusammensetzung hergestellt. Dazu wurde ein Gemenge aus Oxide, Carbonaten und Phosphaten in einem Platin/Rhodium-Tiegel bei einer Temperatur von 1500 bis 1600°C während einer Homogenisierungszeit von einer Stunde erschmolzen. Die Glasschmelze wurde in Wasser abgeschreckt, und die gebildete Glasfritte wurde getrocknet und auf eine mittlere Korngröße von 20 bis 30 µm gemahlen. Das Glaspulver wurde mit handelsüblichen Farbkörpern und Fluoreszenzmitteln versetzt und homogenisiert.First, a starting glass with the one in Table I, Example 18, chemical composition specified. To was a mixture of oxides, carbonates and phosphates in one Platinum / rhodium crucible at a temperature of 1500 to 1600 ° C melted during a homogenization time of one hour. The glass melt was quenched in water, and the one formed Glass frit was dried and to an average grain size of Ground 20 to 30 µm. The glass powder was made with commercially available Color bodies and fluorescent agents are added and homogenized.

    Anschließend wurde das eingefärbte Glaspulver mittels einer uniaxialen Trockenpresse bei Raumtemperatur und bei einem Preßdruck von 750 bar zu zylindrischen Grünlingen mit einer Masse von ca. 4 g gepreßt. Die Grünlinge wurden in einem Brennofen unter Vakuum zur erfindungsgemäßen Glaskeramik in Form eines Rohlings gesintert. In einer ersten Phase wurde der Grünling dazu bei 500°C während 20 Minuten vorgebrannt. Dichtgesintert wurde der Rohling dann in einer zweiten Sinterbehandlung bei 850°C während 30 Minuten, wobei mit einer Aufheizrate von 30°C/min. gearbeitet wurde. Zur Bestimmung der Eigenschaften des glaskeramischen Rohlinges wurde, sofern nicht anders angegeben, so wie in Beispiel 22 vorgegangen.The colored glass powder was then removed using a uniaxial dry press at room temperature and at one Press pressure of 750 bar to form cylindrical green compacts with a mass of about 4 g pressed. The green compacts were placed in a kiln under vacuum to the glass ceramic according to the invention in the form of a Sintered blanks. In the first phase, the green compact was added Pre-baked at 500 ° C for 20 minutes. Was densely sintered the blank is then subjected to a second sintering treatment at 850 ° C for 30 minutes, with a heating rate of 30 ° C / min. was worked. To determine the properties of the glass ceramic Unless otherwise stated, the blank is like proceeded in Example 22.

    RohlingeigenschaftenBlank properties Optische EigenschaftenOptical properties

    Die erhaltenen Rohlinge wiesen vergleichbare optische Eigenschaften, wie Transluzenz, Färbung und Trübung, wie übliche dentalkeramische Verkaufsprodukte, z.B. IPS Empress Dentin 24 Rohlinge von IVOCLAR AG, Liechtenstein, auf. The blanks obtained had comparable optical properties, such as translucency, staining and turbidity, as usual dental ceramic sales products, e.g. IPS Empress Dentin 24 Blanks from IVOCLAR AG, Liechtenstein.

    BiaxialfestigkeitBiaxial strength

    Die Biaxialfestigkeit betrug 270 ± 38 MPa.The biaxial strength was 270 ± 38 MPa.

    Die erhaltenen glaskeramischen Rohlinge wurden schließlich unter Verwendung des Preßverfahrens und Preßofens gemäß EP-A-0 231 773 unter Vakuum im viskosen Zustand in die für den jeweiligen Test gewünschte Probengeometrie verpreßt. Dabei betrugen die Bereitschaftstemperatur des Preßofens 700°C, die Heizrate bis zur Preßtemperatur 60°C/min., die Preßtemperatur 920°C, die Haltezeit bei der Preßtemperatur 10 min. und der Preßdruck 5 bar. Nach dem Preßvorgang wurde die Preßform an der Luft abgekühlt, und die Probenkörper wurden durch Sandstrahlen mit Al2O3-Pulver und Glasperlen entformt.The glass-ceramic blanks obtained were finally pressed in the viscous state into the sample geometry desired for the respective test using the pressing method and pressing furnace according to EP-A-0 231 773. The standby temperature of the press furnace was 700 ° C, the heating rate up to the press temperature 60 ° C / min., The press temperature 920 ° C, the holding time at the press temperature 10 min. and the pressure 5 bar. After the pressing process, the mold was cooled in air and the test specimens were removed from the mold by sandblasting with Al 2 O 3 powder and glass beads.

    Die Eigenschaften der erhaltenen Proben wurden gemäß der in Beispiel 22 jeweils beschriebenen Vorgehensweise bestimmt.The properties of the samples obtained were determined according to the in Example 22 determined procedure described in each case.

    Eigenschaften plastisch verformte GlaskeramikProperties of plastically deformed glass ceramics Optische EigenschaftenOptical properties

    Die plastisch verformte Glaskeramik hatte transluzente Eigenschaften, die es dem Zahntechniker ermöglichen, aus ihr vollkeramische Dentalprodukte, wie z.B. Kronen oder mehrgliedrige Brücken herzustellen, die optisch den Vorgaben eines natürlichen Zahnes entsprechen. Die Kombination von transluzentem Gerüstmaterial und transluzenter bis transparenter Dentalsinterglaskeramik mit einem Ausdehnungskoeffizienten von 9,1 µm/mK, die schichtweise auf das plastisch geformte Kronen- oder Brückengerüst bei 800°C unter Vakuum aufgesintert wurde, führte zu transluzenten, vollkeramischen Dentalrestaurationen, die den hohen ästhetischen Anforderungen an derartige Dentalprodukte genügen. The plastically deformed glass ceramic had translucent properties, which enable the dental technician to make all-ceramic out of it Dental products such as Crowns or multi-unit To create bridges that visually meet the requirements of a natural one Tooth. The combination of translucent framework material and translucent to transparent dental sintered glass ceramic with a coefficient of expansion of 9.1 µm / mK, the layers on the plastically shaped crown or bridge framework 800 ° C sintered under vacuum, led to translucent, All-ceramic dental restorations that meet the high aesthetic Requirements for such dental products are sufficient.

    3-Punkt-Biegefestigkeit3-point bending strength

    Die 3-Punkt-Biegefestigkeit betrug 347 ± 37 MPa.The 3-point bending strength was 347 ± 37 MPa.

    Linearer thermischer AusdehnungskoeffizientLinear coefficient of thermal expansion

    Der im Temperaturbereich von 100 bis 500°C bestimmte Ausdehnungskoeffizient betrug 10,7 µm/mK.The coefficient of expansion determined in the temperature range from 100 to 500 ° C was 10.7 µm / mK.

    Bruchzähigkeit KFracture toughness K 1c1c

    Der ermittelte K1c-Wert betrug 3,8 ± 0,5 MPa √m.The K 1c value determined was 3.8 ± 0.5 MPa √m.

    SäurebeständigkeitAcid resistance

    Der gemäß ISO 6872-1995 bestimmte flächenbezogene Massenverlust nach 16-stündiger Lagerung in 4 Vol.-%iger wäßriger Essigsäurelösung lag deutlich unter dem Normwert für Dentalkeramikmaterialien von 2000 µg/cm2.The area-related mass loss determined according to ISO 6872-1995 after 16 hours' storage in 4% by volume aqueous acetic acid solution was significantly below the standard value for dental ceramic materials of 2000 µg / cm 2 .

    Claims (17)

    1. Sinterable lithium disilicate glass ceramic, characterized in that it contains the following components: Component % by weight SiO2 57.0 to 80.0 Al2O3 0 to 5.0 La2O3 0.1 to 6.0 MgO 0 to 5.0, in particular 0.1 to 5.0 ZnO 0 to 8.0 K2O 0 to 13.5 Li2O 11.0 to 19.0 P2O5 0 to 11.0 Colour components 0 to 8.0 Additional components 0 to 6.0
      where (a) Al2O3 + La2O3 make up from 0.1 to 7.0% by weight and (b) MgO + ZnO make up from 0.1 to 9.0% by weight
      and the colour components are made up of glass-colouring oxides (c) and/or pigments (d) in the following amounts: (c) glass-colouring oxides 0 to 5.0% by weight and (d) pigments 0 to 5.0% by weight.
    2. Lithium disilicate glass ceramic according to Claim 1, characterized in that it consists essentially of the components indicated.
    3. Lithium disilicate glass ceramic according to Claim 1 or 2, characterized in that TiO2, CeO2 and/or Fe2O3 are present as glass-colouring oxides.
    4. Lithium disilicate glass ceramic according to any of Claims 1 to 3, characterized in that it contains doped spinel and/or doped ZrO2 as pigments.
    5. Lithium disilicate glass ceramic according to any of Claims 1 to 4, characterized in that the additional components are B2O3, F, Na2O, ZrO2, BaO and/or SrO.
    6. Lithium disilicate glass ceramic according to any of Claims 1 to 5, characterized in that the amounts of the components are, independently of one another, as follows: Component % by weight SiO2 57.0 to 75.0 Al2O3 0 to 2.5 La2O3 0.1 to 4.0 MgO 0.1 to 4.0 ZnO 0 to 6.0, in particular 0.1 to 5.0 K2O 0 to 9.0, in particular 0.5 to 7.0 Li2O 13.0 to 19.0 P2O5 0 to 8.0, in particular 0.5 to 8.0 Colour components 0.05 to 6.0 Additional components 0 to 3.0.
    7. Process for producing shaped dental products which contain the glass ceramic according to any of Claims 1 to 6, characterized in that
      (a) a starting glass which contains the components as claimed in any of Claims 1 to 6 with the exception of the pigments is melted at temperatures of from 1200 to 1650°C,
      (b) the glass melt is poured into water to form a granulated glass,
      (c) the granulated glass is comminuted to give a powder having a mean particle size of from 1 to 100 µm, based on the number of particles,
      (d) any pigments which are to be present are added to the powder,
      (e) the powder is compacted to form a starting glass blank of desired geometry and heterogeneous structure, and
      (f) the starting glass blank is subjected to one or more heat treatments under reduced pressure in the temperature range from 400 to 1100°C in order to effect sintering to full density and to form a blank of a dental product.
    8. Process according to Claim 7, characterized in that
      (g1) the blank of a dental product is plastically formed at a temperature of from 700 to 1200°C by application of a pressure of from 2 to 10 bar to give a dental product.
    9. Process according to Claim 7, characterized in that
      (g2) the blank of a dental product is machined to give a dental product of desired geometry.
    10. Process according to any of Claims 7 to 9, characterized in that the dental product of desired geometry
      (h) is provided with a coating.
    11. Process according to Claim 10, characterized in that the coating used is a ceramic, a sintered ceramic, a glass ceramic, a glass, a glaze and/or a composite.
    12. Process according to Claim 10 or 11, characterized in that the coating has a sintering temperature of from 650 to 950°C and a linear coefficient of thermal expansion which is less than that of the dental product to be coated.
    13. Process according to any of Claims 10 to 12, characterized in that the coating has a linear coefficient of thermal expansion which differs from that of the dental product of desired geometry by not more than ± 3.0 x 10-6 K-1.
    14. Use of the glass ceramic according to any of Claims 1 to 6 as dental material or component of dental material.
    15. Shaped dental product which contains the glass ceramic as claimed in any of Claims 1 to 6.
    16. Shaped dental product according to Claim 15, characterized in that it is an inlay, an onlay, a bridge, a stump build-up, a facing, a crown or a part-crown.
    17. Glass, characterized in that it contains the components of the glass ceramic according to any of Claims 1 to 6 with the exception of the pigments.
    EP97250239A 1996-09-05 1997-08-15 Sinterable lithium disilicate glass-ceramics Expired - Lifetime EP0827941B1 (en)

    Applications Claiming Priority (4)

    Application Number Priority Date Filing Date Title
    DE19635940 1996-09-05
    DE19635940 1996-09-05
    DE19647739A DE19647739C2 (en) 1996-09-05 1996-11-06 Sinterable lithium disilicate glass ceramic and glass
    DE19647739 1996-11-06

    Publications (2)

    Publication Number Publication Date
    EP0827941A1 EP0827941A1 (en) 1998-03-11
    EP0827941B1 true EP0827941B1 (en) 1999-11-03

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    EP (1) EP0827941B1 (en)
    JP (1) JP3093691B2 (en)
    AT (1) ATE186286T1 (en)
    AU (1) AU695549B2 (en)
    CA (1) CA2213390C (en)

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    Also Published As

    Publication number Publication date
    JP3093691B2 (en) 2000-10-03
    AU3530597A (en) 1998-03-26
    AU695549B2 (en) 1998-08-13
    CA2213390A1 (en) 1998-03-05
    JPH10101409A (en) 1998-04-21
    CA2213390C (en) 2002-07-23
    EP0827941A1 (en) 1998-03-11
    ATE186286T1 (en) 1999-11-15

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